Structure for mounting a semiconductor device on a liquid crystal display, and semiconductor device

ABSTRACT

On a liquid crystal display device ( 80 ) comprising a first substrate ( 81 ) and a second substrate ( 82 ) with electrodes ( 83, 84 ), formed thereon, respectively, and liquid crystal ( 85 ) sealed thereinbetween, a semiconductor device ( 1 ) for driving the liquid crystal display device ( 80 ) is mounted. The semiconductor device ( 1 ) is provided with a plurality of bumps ( 24 ), each electrically conductive with respective electrode pads provided on the upper surface of a semiconductor chip ( 12 ) with an integrated circuit formed thereon, through the intermediary of respective lower electrodes, provided so as to stretch over the upper surface and two sidewall faces of the semiconductor chip ( 12 ), respectively. The semiconductor device ( 1 ) is mounted on the surface of a part of the first substrate ( 81 ) of the liquid crystal display device ( 80 ) where the first substrate ( 81 ) is extended beyond an edge of the second substrate ( 82 ) such that one of the sidewall faces of the semiconductor chip ( 12 ) is opposite thereto, thereby connecting the bumps ( 24 ) to the electrodes ( 83 ) formed on the first substrate ( 81 ), respectively. The other of the sidewall faces of the semiconductor chip ( 12 ) is connected with an end portion of an FPC ( 60 ). As a result, an area of junctions can be lessened, thereby achieving downsizing of the liquid crystal display device.

TECHNICAL FIELD

This invention relates to a structure for mounting a semiconductordevice for driving a liquid crystal display device on a substrate of theliquid crystal display device for electrical and mechanical connectiontherebetween, and the semiconductor device for implementing such astructure, particularly, to a surface-mounting type semiconductor deviceprovided with bumps (protruded electrodes) for electrical connectionwith the liquid crystal display device.

BACKGROUND TECHNOLOGY

Surface-mounting type semiconductor devices have come into widespreaduse as a semiconductor device making up an integrated circuit (IC), alarge scale integrated circuit (LSI), and so forth.

Among the surface-mounting type semiconductor devices, there is one typeprovided with a multitude of bumps placed in lines on the upper surfacethereof for electrical and mechanical connection with a wiring patternon a circuit board when mounting the same on the circuit board. FIG. 15shows the cross-sectional construction of a semiconductor deviceprovided with bumps formed in a straight-wall shape by way of example.

With this semiconductor device, a multitude of electrode pads 74 forconnection with an external circuit are provided along side edges of asemiconductor chip 72, running in a direction orthogonal to the plane ofthe figure, on the surface (the upper face in the figure) of thesemiconductor chip 72 with an integrated circuit (not shown) formedthereon. In FIG. 15, only one of a plurality of the electrode pads 74,74, disposed in respective lines along the side edge on both sides ofthe semiconductor chip 72, is shown.

An insulating film 76 having openings formed in such a way as to cover aperipheral region of the respective electrode pads 74, and to mexposethe inside of the respective peripheral regions is provided on theentire upper surface of the semiconductor chip 72, and a lower electrode79 is provided so as to be in intimate contact with the peripheralregion of the respective openings of the insulating film 76, and anexposed part of the respective electrode pads 74. Further, on top of therespective lower electrodes 79, bumps 78 formed in a straight-wall shapeare provided.

Thus, the semiconductor device is provided with the bumps 78 formed in astraight-wall shape. In contrast, there is another type of semiconductordevice provided with bumps formed in a mushroom shape, wherein the toppart of the bumps is larger than the base thereof. However, thesemiconductor device provided with the bumps formed in a straight-wallshape is more suitable for reducing lateral spread thereof, along asemiconductor substrate 72, and to that extent, a placement density ofthe bumps can be rendered higher, so that a connection pitch with theexternal circuit can be miniaturized.

Such surface-mounting semiconductor devices provided with the bumps asdescribed have come to be used as semiconductor devices for driving aliquid crystal display device, and a plurality of such semiconductordevices for use in driving (scanning and inputting signals) have come tobe mounted on a peripheral region of a glass substrate making up aliquid crystal panel of the liquid crystal display device.

Accordingly, a conventional structure for mounting a semiconductordevice on such a liquid crystal display device is described hereinafterwith reference to FIG. 16 by way of example.

Reference numeral 80 denotes a liquid crystal display device whereinliquid crystal 85 is sealed in-between a first substrate 81 and a secondsubstrate 82, making up a liquid crystal panel, by use of a sealingmaterial 86, and a region 8 of the first substrate 81 where the firstsubstrate 81 is extended beyond an edge of the second substrate 82 is aregion where a semiconductor device 71 for driving the liquid crystaldisplay device 80 is mounted. For the first and second substrates 81,82, respectively, a glass substrate is generally used, however, atransparent resin substrate, or the like may be used as well.

A multitude of scanning electrodes 83 extending to the region 8 from theinterior of the liquid crystal display panel with the liquid crystal 85sealed therein, and a multitude of terminal electrodes 88 serving asconnecting terminals to the external circuit are composed of atransparent and electrically conductive film, and are patterned on theupper surface of the first substrate 81 in such a way as to be placed inlines across the direction orthogonal to the plane of the figure. Amultitude of signal electrodes 84 are composed of a transparent andelectrically conductive film, and are patterned on the inner surface ofthe second substrate 82, opposite to the scanning electrodes 83 acrossthe liquid crystal 85, in such a way as to be placed in lines across thetransverse direction in the figure.

An anisotropic conductive adhesive 50 composed of electricallyconductive particles 52 dispersed in an insulating adhesive is appliedonto the region 8 of the first substrate 81 of the liquid crystaldisplay panel 80. Then, the semiconductor device 71 in a postureinverted from that shown in FIG. 15 is disposed on the region 8 of thefirst substrate 81 after alignment of the respective bumps 78 with therespective scanning electrodes 83 and the respective terminal electrodes88 that are to be connected with the respective bumps 78.

With the semiconductor device 71 being set on the first substrate 81with the anisotropic conductive adhesive 50 applied thereon as describedabove, pressure is applied to the semiconductor device 71 against thefirst substrate 81, and at the same time, heat treatment is appliedthereto, thereby electrically connecting the respective bumps 78 withthe respective scanning electrodes 83 and the respective terminalelectrodes 88 through the intermediary of the electrically conductiveparticles 52 contained in the anisotropic conductive adhesive 50.Concurrently, the semiconductor device 71 is bonded to, and securelymounted on the first substrate 81 by the insulating adhesive containedin the anisotropic conductive adhesive 50.

Further, an end of a flexible printed circuit board (FPC) 60 is disposedon a part of the upper surface of the first substrate 81 where theterminal electrodes 88 are formed. A wiring pattern (not shown) composedof a copper foil, for providing the semiconductor device 71 with a powersupply source and input signals, is formed on the FPC 60.

The wiring pattern is also electrically connected with the respectiveterminal electrodes 88 on the first substrate 81 through theintermediary of the electrically conductive particles 52 contained inthe anisotropic conductive adhesive 50, and at the same time, the end ofthe FPC 60 is bonded to, and securely mounted on the first substrate 81.

By mounting the semiconductor device 71 in the manner as describedabove, the electrically conductive particles 52 contained in theanisotropic conductive adhesive 50 are securely held between therespective bumps 78 and the respective scanning electrodes 83 on thefirst substrate 81 as well as between the wiring pattern on the FPC 60and the respective terminal electrodes 88 on the first substrate 81,thereby attaining electrical connection, respectively, and alsoattaining mechanical connection therebetween, respectively, by theinsulating adhesive.

Thereafter, a mold resin 62 is applied to the upper surface of junctionsfor both the semiconductor device 71 and the FPC 60, as well asperipheral regions thereof. This can prevent moisture from ingressinginto junctions between the respective bumps 78 and the respectivescanning electrodes 83 as well as junctions between the FPC 60 and therespective terminal electrodes 88 while providing these junctions withmechanical protection, so that reliability of the structure for mountingthe semiconductor device can be enhanced.

However, a problem has been encountered with such a conventionalstructure of mounting the semiconductor device on a liquid crystaldisplay device, that is, an area occupied by those junctions (the region8 shown in FIG. 16) requires a fairly large size, thus interfering withan aim of downsizing the liquid crystal display device.

For example, the region 8 representing a junction area for joining boththe semiconductor device 71 and the FPCs 60 with the liquid crystaldisplay device 80 was found to be about 5 mm in width since it wasnecessary to take into account 2 mm as a width of the semiconductordevice 71, 1 mm as connection allowance for the semiconductor device 71,and 2 mm as connection allowance for the FPC 60.

The region 8 of the liquid crystal display device 80, in which thesemiconductor device is mounted, represents non-display sections of theliquid crystal panel, so that a module size of the liquid crystal panelhas come to represent a fairly large proportion relative to a displaysection area.

DISCLOSURE OF THE INVENTION

The invention has been developed to solve the problem described above,and it is therefore an object of the invention to realize downsizing ofa liquid crystal display device by reducing an area of a part of theliquid crystal display device, for mounting a semiconductor device on acircuit board thereof, including a part of the liquid crystal displaydevice, for connecting a flexible printed circuit board to thesemiconductor device. To this end, the invention provides a structurefor mounting a semiconductor device on a liquid crystal display device,and the semiconductor device for implementing the structure.

More specifically, with a structure for mounting a semiconductor deviceon a liquid crystal display device according to the invention, thesemiconductor device provided with bumps electrically conductive withelectrode pads formed on a semiconductor chip with an integrated circuitformed thereon, respectively, through the intermediary of respectivelower electrodes, formed so as to stretch over both the surface (uppersurface) and a sidewall face of the semiconductor chip, is mounted onthe liquid crystal display device comprising a first substrate providedwith scanning electrodes formed thereon, a second substrate providedwith signal electrodes formed thereon opposite to the scanningelectrodes, and liquid crystal sealed therein-between. Further, thesemiconductor device is mounted on the surface of a part of either ofthe first substrate and the second substrate, where one of thesubstrates is extended beyond an edge of the other substrate, such thatone sidewall face of the semiconductor chip is opposite the surface, sothat the bumps disposed on the side are connected to the electrodesformed on one of the substrates, respectively.

The bumps of the semiconductor device are preferably provided so as tostretch over both the surface (upper surface) and a second sidewall faceof the semiconductor chip opposite from a first sidewall face thereof aswell as both the upper surface and the first sidewall face, and thesemiconductor device is preferably mounted on the surface of the part ofeither of the first substrate and the second substrate, where one of thesubstrates is extended beyond the edge of the other substrate, such thatthe first sidewall face of the semiconductor chip is opposite thesurface, so that the bumps stretching over the first sidewall face areconnected to the electrodes formed on said one of the substrates,respectively, while a flexible printed circuit board is connected to thesecond sidewall face of the semiconductor chip, so that a wiring pattern(printed wiring) of the flexible printed circuit board is renderedelectrically conductive with the bumps stretching over the secondsidewall face.

Otherwise, the bumps of the semiconductor device may be provided so asto stretch over both the surface (upper surface) and a third sidewallface of the semiconductor chip orthogonal to a first sidewall facethereof as well as both the upper surface and the first sidewall face,and the semiconductor device is mounted on the surface of the part ofeither of the first substrate and the second substrate, where one of thesubstrates is extended beyond the edge of the other substrate, such thatthe first sidewall face of the semiconductor chip is opposite thesurface, so that the bumps stretching over the first sidewall face areconnected to the electrodes formed on said one of the substrates,respectively, while a flexible printed circuit board is connected to thethird sidewall face of the semiconductor chip, so that a wiring pattern(printed wiring) of the flexible printed circuit board is renderedelectrically conductive with the bumps stretching over the thirdsidewall face.

Further, a semiconductor device according to the invention is asemiconductor device to be mounted on the liquid crystal display devicecomprising a first substrate provided with scanning electrodes formedthereon, a second substrate provided with signal electrodes formedthereon, opposite to the scanning electrodes, and liquid crystal sealedtherein-between, for driving the liquid crystal display device,comprising: a semiconductor chip provided with an integrated circuitformed thereon with a plurality of electrode pads for connecting theintegrated circuit to an external circuit, disposed in the vicinity ofside edges of the upper surface thereof; an insulating film formed onthe semiconductor chip, having an opening for exposing the respectiveelectrode pads; a lower electrode provided on the respective electrodepads; and a plurality of bumps, each electrically conductive with therespective electrode pads through the intermediary of the respectivelower electrodes, provided so as to stretch over both the surface (uppersurface) and respective sidewall faces of the semiconductor chip.

The sidewall faces of the semiconductor chip, along which the bumps areprovided, respectively, are preferably formed in a setback shape with adifference in level, provided on the side of the surface (upper surface)of the semiconductor chip.

Further, it is desirable that the bumps are provided so as to protrudesideways from the respective sidewall faces of the semiconductor chip.In the case where the sidewall faces of the semiconductor chip areformed in the setback shape with the difference in level, the bumps arepreferably provided so as to protrude sideways from the outermost faceof the respective sidewall faces.

Further, the bumps are preferably composed of a plurality of metalliclayers composed of, for example, a copper layer and a gold layer, or acopper layer, a nickel layer, and a gold layer, deposited in this orderfrom the lower electrode side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an embodiment of a structure formounting a semiconductor device on a liquid crystal display deviceaccording to the invention;

FIG. 2 is a sectional view showing an embodiment of a semiconductordevice to be mounted on a liquid crystal display device according to theinvention;

FIGS. 3 to 10 are sectional views showing respective steps of a methodof fabricating the semiconductor device shown in FIG. 2;

FIG. 11 is a perspective view showing an example of a relationship ofthe semiconductor device in the invention with a substrate of the liquidcrystal display device, and with a FPC;

FIG. 12 is a plan view showing a part of the liquid crystal displaydevice shown in FIG. 11 with the semiconductor device mounted thereon,and with the FPCs connected thereto;

FIG. 13 is a perspective view showing another example of a relationshipof the semiconductor device in the invention with the substrate of theliquid crystal display device, and with the FPC;

FIG. 14 is a plan view showing a part of the liquid crystal displaydevice shown in FIG. 13 with the semiconductor device mounted thereon,and the FPCs connected thereto;

FIG. 15 is a sectional view showing an example of a conventionalsemiconductor device provided with bumps; and

FIG. 16 is a sectional view showing an example of a conventionalstructure for mounting the semiconductor device on a liquid crystaldisplay device.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of a structure for mounting a semiconductor deviceon a liquid crystal display device, and a semiconductor device forimplementing the structure, according to the invention, are describedhereinafter with reference to the accompanying drawings.

Construction of a Semiconductor Device: FIG. 2

First, an embodiment of a semiconductor device to be mounted on a liquidcrystal display device, according to the invention, is describedhereinafter with reference to FIG. 2.

FIG. 2 is a sectional view showing the construction of a surfacemountingtype semiconductor device according to the invention, which is to bemounted on a liquid crystal display device for driving the liquidcrystal display device.

The semiconductor device 1 comprises a semiconductor chip 12 providedwith an integrated circuit (not shown in the figure) formed thereon, andelectrode pads 14 for connecting the integrated circuit to an externalcircuit, disposed in the vicinity of side edges (in this example, anedge of sidewall faces 12 b, 12 c, on opposite sides of thesemiconductor chip 12, respectively, running in a direction orthogonalto the plane of the figure) of a surface (upper surface) 12 a thereof;an insulating film 16 formed on the semiconductor chip 12, having anopening 16 a for exposing respective electrode pads 14; a lowerelectrode 19 provided on top of the respective electrode pads 14, andbumps 24, each electrically conductive with the respective electrodepads 14 via the respective lower electrodes 19, provided so as tostretch over both the upper surface 12 a of the semiconductor chip 12and the first sidewall 12 b or the second sidewall 12 c, opposite thefirst sidewall 12 b.

The sidewall faces 12 b, 12 c of the semiconductor chip 12, along whichthe bumps 24 are provided, respectively, are formed in a setback shapewith a difference in level (steps 12 d, 12 e), provided on the side ofthe upper surface 12 a, and the lower electrode pad 19 is extended fromthe respective electrode pads 14 along the step section, with therespective bumps 24 being formed in such a way as to overlie therespective lower electrodes 19.

The sidewall face of the respective bumps 24 are protruded sideways tothe extent of 1 to 10 μm from the sidewall face 12 b or 12 c of thesemiconductor chip 12, that is, the outermost face of the respectivesidewall faces having the difference in level. The bumps 24 are composedof two metallic layers, namely, an inner bump 22 formed of a copper (Cu)layer, and an outer bump 23 formed of a gold (Au) layer.

In this connection, the bumps 24 may be composed of a single metalliclayer insusceptible to oxidation such as a gold, or may be composed ofthree layers consisting of a copper layer, a nickel layer, and a goldlayer, or so forth.

Structure for Mounting the Semiconductor Device: FIG. 1

The structure wherein the semiconductor device is mounted on a liquidcrystal display device is described hereinafter with reference to FIG.1.

Reference numeral 80 denotes a liquid crystal display device, andrespective parts composing a liquid crystal display panel thereof,corresponding to those of the conventional liquid crystal display deviceshown in FIG. 16, are denoted by like reference numerals.

The semiconductor device 1 for driving the liquid crystal display device80 is mounted on the liquid crystal display device 80 comprising a firstsubstrate 81 that is a glass substrate provided with scanning electrodes83 formed thereon, a second substrate 82 that is a glass substrateprovided with signal electrodes 84 formed thereon opposite to thescanning electrodes 83, and liquid crystal 85 sealed therein-betweenwith a sealing material 86.

As described hereinbefore with reference to FIG. 2, the semiconductordevice 1 is provided with the bumps 24 formed in such a way as tostretch over both the upper surface 12 a of the semiconductor chip 12with the integrated circuit formed thereon, and the first sidewall face12 b or the second sidewall face 12 c.

With the semiconductor device 1 set up in a posture as shown in FIG. 1,a sidewall face on one side of the semiconductor chip 12 is opposite to,and mounted on a region (part) of the first substrate 81 of the liquidcrystal display device 80 where the first substrate 81 is extendedbeyond an edge of the second substrate 82, and the bumps 24 shown on thelower side in the figure are connected to the scanning electrodes 83formed on the first substrate 81, respectively.

An anisotropic conductive adhesive 50 composed of electricallyconductive particles dispersed into an insulating adhesive is interposedbetween the respective bumps 24, and the respective scanning electrodes83 on the first substrate 81, and thereafter heat treatment is appliedtherebetween while applying pressure to the semiconductor device 1against the first substrate 81, thereby attaining electrical connectionbetween the respective bumps 24 and the respective scanning electrodes83 through the intermediary of the electrically conductive particles.

Further, an end of a flexible printed circuit board (FPC) 60 is presseddown to another sidewall face on the upper side of the semiconductorchip 1, as shown in the figure, and bonded thereto by the anisotropicconductive adhesive 50, thereby attaining electrical connection(conduction) between the respective bumps 24 disposed on the upper sidein the figure, and a wiring pattern formed on the FPC 60 through theintermediary of the electrically conductive particles of the anisotropicconductive adhesive 50.

For connection of the respective bumps 24 of the semiconductor device 1with the respective scanning electrodes 83 on the first substrate 81 ofthe liquid crystal display device 80, and with the wiring pattern formedon the FPC 60, heat treatment at a temperature in the range of 180 to220° C. is applied between the FPC 60 and the semiconductor device 1 aswell as between the semiconductor device 1 and the first substrate 81while applying pressure at 400 kg/cm² thereto, respectively.

Thereafter, a gap between the periphery of the semiconductor device 1,and the first and second substrates 81, 82, of the liquid crystaldisplay device 80, respectively, and a gap between the periphery of thesemiconductor device 1, and the FPC 60 are filled up, and covered withmold resin 65, thereby preventing moisture from ingressing intorespective junctions, and providing the respective junctions withmechanical protection while ensuring that the semiconductor device 1,the liquid crystal display device 80, and the FPC 60 are solidly bondedtogether.

Thus, by electrically and mechanically connecting the sidewall face ofthe semiconductor chip 12 of the semiconductor device with the substrateof the liquid crystal display device and the electrodes formed thereon,an area required for mounting the semiconductor device on the substrateof the liquid crystal display device can be significantly reduced incomparison with that in the case of the conventional structure formounting a semiconductor device, as shown in FIG. 16, so that nondisplaysections of a liquid crystal display panel are lessened in area, therebyenabling a liquid crystal display device to be downsized.

Method of Fabricating the Semiconductor Device: FIGS. 2 to 10

A method of fabricating the semiconductor device shown in FIG. 2,according to the invention, is next described with reference to FIGS. 3to 10.

As shown in FIG. 3, a first dicing (grooving) step is applied to asurface 10 a of a semiconductor substrate (wafer) 10 provided withintegrated circuits (not shown) for a multitude of semiconductor chips,and a multitude of electrode pads 14 placed in lines on the surface 10 athereof, thereby forming a street line 10 s in the shape of a groove.The street line 10 s is formed in the central region between respectivelines of the electrode pads 14 for the semiconductor chips 12, 12adjacent to each other and arranged in two lines, to a depth so as toleave out a thickness t of the semiconductor substrate 10, in the orderof, for example, 200 to 300 μm.

The respective electrode pads 14 are made of aluminum and have thefunction of connecting a multitude of the integrated circuits fordriving the liquid crystal display device, formed in the semiconductorsubstrate 10, with an external circuit, respectively.

Subsequently, as shown in FIG. 4, an insulating film 16 made of aphotosensitive polyimide is formed on the surface (upper surface) 10 aof the semiconductor substrate 10, and on the entire inner surface ofthe street line 10s to a thickness in the range of 2 to 3 μm by the spincoater method. The insulating film 16 may be composed of a silicon oxidefilm containing boron and/or phosphorus, formed by the chemical vapordeposition (CVD) method, besides a photosensitive polyimide film, or maybe composed of a silicon nitride film formed by the plasma CVD method.

Thereafter, by applying exposure treatment to the insulating film 16composed of the photosensitive polyimide film using a predeterminedmask, and subsequently, by applying development treatment thereto, theinsulating film 16 is patterned such that an opening 16 a is formed,over the respective electrode pads 14, as shown in FIG. 5.

In a subsequent step, an aluminum film, a chromium film, and a copperfilm are formed in sequence by the sputtering method to a thickness of0.8 μm, 0.01 μm, and 0.8 μm, respectively, on the entire upper surfaceof the semiconductor substrate 10 including the upper surface of theinsulating film 16 and that of the respective electrode pads 14, therebyforming a common electrode film 18 of a triple-layer structure as shownin FIG. 6.

As a constituent material for the common electrode film 18, it isnecessary to select a stable electrode material that has excellentelectrical connection and mechanical adhesion with an electrode materialused for forming the electrode pads 14 and the inner bumps 22 shown inFIG. 2, and that causes no mutual diffusion with the latter electrodematerial.

For this reason, besides the above-described triple-layer structurecomposed of aluminum, chromium, and copper, either a bi-layer structurecomposed of titanium and palladium, titanium and gold, titanium andplatinum, titanium-tungsten alloy and palladium, titanium-tungsten alloyand gold, titanium-tungsten alloy and platinum, titanium-tungsten alloyand copper, chromium and copper, and so forth, or a triple-layerstructure composed of aluminum, titanium, and copper is effective forthe common electrode film 18.

In this connection, the uppermost layer of the common electrode film 18is preferably made of copper because this will render it easier to formthe bumps by plating as described later, and further, even if solderingis applied to the upper surface of copper, there will be no risk ofcopper melting into solder upon heating in this case.

Subsequently, as shown in FIG. 7, a photosensitive resin 20 is formedover the entire upper surface of the common electrode film 18 in athickness of 17 μm by the spin coater method. Further, after applyingexposure treatment to the photosensitive resin 20 using a predeterminedmask, development treatment is applied thereto, so that thephotosensitive resin film 20 is patterned such that an opening is formedin respective regions where the respective bumps are to be formed (referto FIG. 8).

In a subsequent step, a copper plating is formed to a thickness rangingfrom 10 μm to 15 μm using the photosensitive resin film 20 as a platingmask, thereby forming the inner bump 22 composed of a copper platinglayer on the common electrode film 18 inside the respective openings ofthe photosensitive resin 20 as shown in FIG. 8.

Further, as a constituent material for the inner bumps 22 formed at thispoint in time, gold or nickel may be used instead.

In a subsequent step, the photosensitive resin 20 that have been used asthe plating mask is removed by use of a wet remover (refer to a FIG. 9).Thereafter, etching of copper is carried out using the inner bumps 22 asetching masks by use of “Enstrip C” (trade name) which is the etchantfor copper, manufactured by Meltex Inc., thereby removing portions ofcopper which is the uppermost layer coating of the common electrode film18, in regions exposed out of the respective inner bumps 22. Such anetching treatment is applied for the duration of an over-etching time,30% longer than a just etching time.

Subsequently, the chromium film (an intermediate layer), serving as abarrier layer as well as an adhesion layer of the common electrode film18, and the aluminum film (the bottom layer) of the common electrodefilm 18 are etched with a mixed liquid consisting of ammonium ceriumnitrate, potassium ferricyanide, and sodium hydroxide. This etchingtreatment is also applied for the duration of an over-etching time, 30%longer than a just etching time.

Thus, by removing unnecessary portions of the common electrode film 18,a lower electrode 19 can be formed only in underlayer regions matchingthe respective inner bumps 22 as shown in FIG. 9.

Thereafter, in a second dicing step, a portion of the semiconductorsubstrate 10, underneath the street line 10 s, the thickness of whichhas been rendered thinner in the first dicing step as described withreference to FIG. 3, is cut off, thereby cutting the semiconductorsubstrate 10 into individual semiconductor chips 12. The second dicingstep is carried out with a dicing width W narrower to the extent in therange of 30 to 50 μm than that for the first dicing step.

Thereafter, the entire exposed surface of the respective inner bumps 22of the respective semiconductor chips 12 is plated with gold to athickness in the range of 2 to 3 μm by the electroless plating method,thereby forming an outer bump 24 as shown in FIG. 2.

In this connection, the outer bump 24 may have a bi-layer structurecomposed of nickel and gold.

After taking the steps described in the foregoing in sequence, thesemiconductor device 1 is completed wherein, as shown in FIG. 2, amultitude of the bumps 24 are formed so as to stretch over both theupper surface 12 a of the semiconductor chips 12 and the first sidewallface 12 b as well as both the upper surface 12 a and the second sidewallface 12 c opposite from the first sidewall face 12 b, respectively, andto be insulated from each other by the insulating film 16. SupplementaryDescription of the Semiconductor Device and the Structure for Mountingthe Same: FIGS. 11 to 14

Now, supplementary description is given hereinafter on the semiconductordevice 1 and the structure for mounting the same on a liquid crystaldisplay device with reference to FIGS. 11 to 14.

With the semiconductor device 1 shown in FIG. 2, a plurality of thebumps 24 formed so as to stretch over both the upper surface 12 a of thesemiconductor chip 12 and the first sidewall face 12 b are placed inlines at a spacing across the longitudinal direction, and a plurality ofthe bumps 24 formed so as to stretch over both the surface 12 a and thesecond sidewall face 12 c are also placed in lines at a spacing acrossthe longitudinal direction as shown in FIG. 11. The first sidewall face12 b and the second sidewall face 12 c are respective sidewall faces onopposite sides of the semiconductor chip 12, parallel to each other.

In this case, as shown in FIG. 11, the semiconductor device 1 is mountedon the upper surface of the first substrate 81 of the liquid crystaldisplay device such that the first sidewall face 12 b of thesemiconductor chip 12 is opposite thereto and an end portion of the FPC60 is connected with the second sidewall face 12 c. In FIG. 11, thefirst substrate 81 and the FPC 60 are indicated by phantom lines.

FIG. 12 is a plan view showing a part of the liquid crystal displaydevice 80 wherein the semiconductor devices 1 are mounted, and the FPC60 is connected to the respective semiconductor devices 1.

FIGS. 13 and 14 are views similar to FIGS. 11 and 12, showing anotherembodiment of the invention, different from the previously describedembodiment, by way of example.

With a semiconductor device 1′ according to this example, bumps 24 areprovided so as to stretch over both the upper surface 12 a of asemiconductor chip 12 and a first sidewall face 12 b, and other bumps 24are also provided so as to stretch over both the upper surface 12 a ofthe semiconductor chip 12 and a third sidewall face 12 f of thesemiconductor chip 12, orthogonal to the first sidewall face 12 b. Inother respects, the semiconductor device 1′ is the same in constructionas the semiconductor device 1 shown in FIG. 2.

As shown in FIGS. 13 and 14, in mounting the semiconductor device 1′ onthe liquid crystal display device, the semiconductor device 1′ ismounted on the upper surface of a portion of the first substrate 81 ofthe liquid crystal display device 80, extending beyond an edge of thesecond substrate 82 thereof, such that the first sidewall face 12 b ofthe semiconductor chip 12 is opposite thereto, thereby connecting therespective outer bumps 24 stretching over the first sidewall face 12 bwith respective scanning electrodes 83 on the first substrate 81.Further, the flexible printed circuit board (FPC) 60 is connected to thethird sidewall face 12 f of the semiconductor chip 12 of the respectivesemiconductor device 1′, thereby causing the respective outer bumps 24provided to stretch over the third sidewall face 12 f to be electricallyconductive with a printed wiring of the FPC 60.

The construction as described above results in a decrease in thedimensions of the liquid crystal display device, thicknesswise, and thisis advantageous in fabricating a flat-type liquid crystal displaydevice.

With each of the previously-described embodiments, the semiconductordevice is mounted on the first substrate of the liquid crystal displaydevice, with the scanning electrodes formed thereon, but the same may bemounted on the second substrate thereof in case that the secondsubstrate with the signal electrodes formed thereon is extended beyondan edge of the first substrate. Further, semiconductor devices to beconnected with the scanning electrodes may be mounted on the firstsubstrate while semiconductor devices to be connected with the signalelectrodes may be mounted on the second substrate. Furthermore, theremay be a case where the scanning electrodes and the signal electrodesare installed in a reversed position, respectively, or serve as displayelectrodes or data electrodes and opposite electrodes, respectively.

INDUSTRIAL APPLICABILITY

As is evident from the foregoing description, with the structure formounting the semiconductor device on the liquid crystal display device,and the semiconductor device for implementing the same, according to theinvention, the semiconductor device for driving the liquid crystaldisplay device is provided with the bumps formed so as to stretch overboth the upper surface and the sidewall faces of the semiconductor chip,so that connection of the semiconductor chip with the circuit board ofthe liquid crystal display device, and the flexible printed circuitboard for providing the semiconductor device with a power supply sourceand signals is effected on the sidewall faces of the semiconductor chip,respectively. Accordingly, an area of junctions can be downsized, andfurther, connection can be rendered highly reliable.

As a result, it becomes possible to realize high density mounting ofsemiconductor devices on a liquid crystal display device, therebyachieving downsizing of the liquid crystal display device.

What is claimed is:
 1. A structure for mounting a semiconductor deviceon a liquid crystal display device for driving the liquid crystaldisplay device comprising a first substrate provided with scanningelectrodes formed thereon, a second substrate provided with signalelectrodes formed thereon, opposite to the scanning electrodes, andliquid crystal sealed therein-between, wherein said semiconductor deviceis provided with bumps electrically conductive with electrode padsformed on a semiconductor chip with an integrated circuit formedthereon, respectively, through an intermediary of respective lowerelectrodes, formed so as to stretch over both an upper surface and asidewall face of the semiconductor chip, and said semiconductor deviceis mounted on a surface of a part of either the first substrate and thesecond substrate, where one of said substrates is extended beyond anedge of the other substrate, such that the sidewall face on one side ofthe semiconductor chip is opposite to said surface, so that the bumpsdisposed on said one side are connected to the electrodes formed on oneof said substrates, respectively.
 2. A structure for mounting asemiconductor device on the liquid crystal display device according toclaim 1, wherein the bumps of said semiconductor device are provided soas to stretch over both the upper surface and a second sidewall face ofthe semiconductor chip opposite from a first sidewall face of thesemiconductor chip as well as both the upper surface and the firstsidewall face, and said semiconductor device is mounted on the surfaceof a part of either the first substrate and the second substrate, whereone of said substrates is extended beyond an edge of the othersubstrate, such that the first sidewall face of the semiconductor chipis opposite to said surface, so that the bumps stretching over the firstsidewall face are connected to the electrodes formed on said one of thesubstrates, respectively, while a flexible printed circuit board isconnected to the second sidewall face of the semiconductor chip, so thata printed wiring of the flexible printed circuit board is renderedelectrically conductive with the bumps stretching over the secondsidewall face.
 3. A structure for mounting a semiconductor device on theliquid crystal display device according to claim 1, wherein the bumps ofsaid semiconductor device are provided so as to stretch over both theupper surface and a third sidewall face of the semiconductor chiporthogonal to a first sidewall face of the semiconductor chip as well asboth the upper surface and the first sidewall face, and saidsemiconductor device is mounted on the surface of a part of either thefirst substrate and the second substrate, where one of said substratesis extended beyond an edge of the other substrate, such that the firstsidewall face of the semiconductor chip is opposite to said surface, sothat the bumps stretching over the first sidewall face are connected tothe electrodes formed on said one of the substrates, respectively, whilea flexible printed circuit board is connected to the third sidewall faceof the semiconductor chip, so that a printed wiring of the flexibleprinted circuit board is rendered electrically conductive with the bumpsstretching over the third sidewall face.
 4. A semiconductor devicemounted on a liquid crystal display device comprising a first substrateprovided with scanning electrodes formed thereon, a second substrateprovided with signal electrodes formed thereon opposite to the scanningelectrode, and liquid crystals sealed therein-between, for driving theliquid crystal display device; said semiconductor device comprising: asemiconductor chip provided with an integrated circuit formed thereon,and electrode pads for connecting the integrated circuit to an externalcircuit, disposed in the vicinity of side edges of the upper surfacethereof; an insulating film formed on the semiconductor chip, having anopening for exposing the respective electrode pads; a lower electrodeprovided on the respective electrode pads; and a plurality of bumps,each electrically conductive with the respective electrode pads throughthe intermediary of the respective lower electrodes, provided so as tostretch over both the upper surface and respective sidewall faces of thesemiconductor chip.
 5. A semiconductor device according to claim 4,wherein the sidewall faces of the semiconductor chip, along which thebumps are provided, respectively, are formed in a setback shape with adifference in level, provided on the side of the upper surface of thesemiconductor chip.
 6. A semiconductor device according to claim 4,wherein the bumps are provided so as to protrude sideways from therespective sidewall faces of the semiconductor chip.
 7. A semiconductordevice according to claim 5, wherein the bumps are provided so as toprotrude sideways from an outermost face of the respective sidewallfaces having the difference in level, of the semiconductor chip.
 8. Asemiconductor device according to claim 4, wherein the bumps arecomposed of a plurality of metallic layers.
 9. A semiconductor deviceaccording to claim 6, wherein the bumps are composed of a plurality ofmetallic layers.
 10. A semiconductor device according to claim 7,wherein the bumps are composed of a plurality of metallic layers.